Digital voice privacy apparatus and method

Abstract

A cellular voice privacy arrangement includes a digital privacy unit which is part of each subscriber's fixed equipment. The digital privacy unit includes suitable analog to digital and digital to analog converters. A vocoder, digital signal processor and modem provide the privacy. The identification numbers of each terminal (phone) are exclusive-ORed to form a scramble variable. Vocoder data (voice coded information) is exclusive-ORed with the scramble variable to provided scrambled data for transmission.

What is claimed is: 
     
       1. A digital voice privacy unit for providing secure communications between subscribers' telephones in a telecommunication system, said digital voice privacy unit comprising: a vocoder for converting voice information of a first telephone to digital data;   a digital signal processor for scrambling said digital data of said first telephone with a scramble variable to produce scrambled digital data, said digital signal processor coupled to said vocoder;   said digital signal processor includes means for producing said scramble variable;   said first telephone and said second telephone each include an identification number;   said means for producing includes first means for exclusive-ORing said identification number of said first telephone with said identification number of said second telephone; and   a modem for transmitting said scrambled digital data to a second telephone via said telecommunication system, said modem coupled to said digital signal processor and to said telecommunication system.   
     
     
       2. A digital voice privacy unit as claimed in claim 1, wherein there is further included second means for exclusive-ORing said scramble variable with said digital data to produce said scrambled digital data. 
     
     
       3. A digital voice privacy unit as claimed in claim 1, wherein said telecommunication system includes a cellular telecommunication system. 
     
     
       4. A digital voice privacy unit as claimed in claim 1, wherein said vocoder, said digital signal processor, and said modem are each included on a single integrated circuit. 
     
     
       5. A digital voice privacy unit for providing secure communications between subscribers' telephones in a telecommunication system, said digital voice privacy unit comprising: a modem for receiving scrambled digital data from a first telephone via said telecommunication system;   a digital signal processor for descrambling said scrambled digital data of said first telephone with a scramble variable to produce digital data, said digital signal processor coupled to said modem;   said digital signal processor includes means for producing said scramble variable;   said first telephone and said second telephone each include an identification number;   said means for producing includes first means for exclusive-ORing said identification number of said first telephone with said identification number of said second telephone; and   a vocoder for converting said digital data to voice information for a second telephone, said vocoder coupled to said digital signal processor.   
     
     
       6. A digital voice privacy unit as claimed in claim 5, wherein there is further included second means for exclusive-ORing said scramble variable with said digital data to produce said scrambled digital data. 
     
     
       7. A digital voice privacy unit as claimed in claim 5, wherein said telecommunication system includes a cellular telecommunication system. 
     
     
       8. A digital voice privacy unit as claimed in claim 5, wherein said vocoder, said digital signal processor, and said modem are each included on a single integrated circuit. 
     
     
       9. A method for digital voice privacy between a first telephone and a second telephone of a telecommunication system, said method comprising the steps of: training a modem of said first telephone and a modem of said second telephone to establish a connection between said first telephone and said second telephone;   exchanging by said first telephone and said second telephone a first identification number of said first telephone and a second identification number of said second telephone;   producing a scramble variable by said first telephone and said second telephone from said first identification number and said second identification number;   said step of producing a scramble variable includes the step of exclusive-ORing said first identification number and said second identification number;   converting by a vocoder voice information of said first telephone to digital data;   scrambling by a digital signal processor said digital data of said first telephone with said scramble variable to produce scrambled digital data; and   transmitting by a modem said scrambled digital data of said first telephone to a modem of said second telephone.   
     
     
       10. A method for digital voice privacy as claimed in claim 9, wherein there is further included the step of converting said scrambled digital data to analog data for transmission to said second telephone. 
     
     
       11. A method for digital voice privacy as claimed in claim 10, wherein there is further included the step of converting said analog data received by said second telephone to scrambled digital data. 
     
     
       12. A method for digital voice privacy as claimed in claim 9, wherein there is further included the steps of: receiving by said modem of said second telephone said scrambled digital data;   descrambling by a digital signal processor of said second telephone said scrambled digital data to produce digital data; and   converting by a vocoder of said second telephone said digital data to voice information.